Since their discovery lasers have been advocated as alternatives to conventional clinical methods for a wide range of medical applications. For many years high-powered and highly focused lasers have been used to cut and separate tissue in many surgical techniques. More recently, therapeutic and biostimulating properties of laser radiation were discovered. It is believed that laser radiation stimulates several metabolic processes, including cell division, synthesis of hemoglobin, collagen and other proteins, leukocyte activity, production of macrophage cells and wound healing. In this case the laser radiation acts as a stimulating agent on the cell activity and activates therewith the body's own healing capability.
Laser therapy is often used to give relief for both acute and chronic pain, resolve inflammation, increase the speed, quality and tensile strength of tissue repair, resolve infection and improve the function of damaged neurological tissue. This therapy is based on the application of narrow spectral width light over injuries or lesions to stimulate healing within those tissues. Treatment with laser beams is painless and causes neither a macrochemical change nor damage in the tissue.
Up to now the actual mechanism of action underlying the laser effects has not yet been fully understood. According to one theory, the energy of laser radiation is incorporated in natural processes in a manner similar to that by which the “quanta” of light are incorporated in the chain of reactions of plant photosynthesis. Another theory is based on the assumption that cells and tissues have a certain reserve of free charge and are surrounded by a particular biological field such that the interconnections among organism, organs, apparatus and tissues are not determined by mechanisms of humeral, nervous and chemical regulations only, but also by more complex energetic connections.
The lack of understanding of the basic mechanisms underlying the effects of laser application resulted in a diverse range of therapeutic devices and protocols using laser in very different ways and with different wavelength. Several U.S. patents have been granted for different apparatus and methods based on the laser application for therapeutic treatment of living tissue by laser irradiation. Among them the following are particularly relevant: U.S. Pat. No. 4,671,258 to Walker; U.S. Pat. No. 4,930,504 to Diamantopoulos et al.; U.S. Pat. No. 4,931,053 to L'Esperance, Jr.; U.S. Pat. Nos. 5,445,146 and 5,951,596 to Bellinger; and U.S. Pat. No. 5,755,752 to Segal, all of which are incorporated herein by reference in their entireties.
All the above mentioned patents, as well as most works in this field, refer to use of lasers at “low” or “medium” power level. This kind of therapy is now popularly referred to LLLT (Low Level Laser Therapy) or LILT (Low Intensity Laser Therapy). The power range used in LLLT is between few mW and 1,000 mW.
LLLT has become a popular treatment in a variety of medical disciplines. This therapy is used with some success but results are obtained only slowly and are inconsistent. The degree of therapeutic effect achieved is variable and heavily depends upon the dosage of luminous wave, exposure rhythm, and the distance of the treated tissue from the laser source. Applications of several minutes are repeated at intervals of several days and often repeated for months.